Internals: Added LastActiveId, LastActiveIdTimer. (#1537)

imgui.cpp

@@ -1929,7 +1929,14 @@ void ImGui::SetActiveID(ImGuiID id, ImGuiWindow* window)
     ImGuiContext& g = *GImGui;
     g.ActiveIdIsJustActivated = (g.ActiveId != id);
     if (g.ActiveIdIsJustActivated)
+    {
         g.ActiveIdTimer = 0.0f;
+        if (id != 0)
+        {
+            g.LastActiveId = id;
+            g.LastActiveIdTimer = 0.0f;
+        }
+    }
     g.ActiveId = id;
     g.ActiveIdAllowOverlap = false;
     g.ActiveIdIsAlive |= (id != 0);
@@ -2308,6 +2315,7 @@ void ImGui::NewFrame()
         ClearActiveID();
     if (g.ActiveId)
         g.ActiveIdTimer += g.IO.DeltaTime;
+    g.LastActiveIdTimer += g.IO.DeltaTime;
     g.ActiveIdPreviousFrame = g.ActiveId;
     g.ActiveIdIsAlive = false;
     g.ActiveIdIsJustActivated = false;

imgui_internal.h

@@ -533,6 +533,8 @@ struct ImGuiContext
     bool                    ActiveIdAllowOverlap;               // Active widget allows another widget to steal active id (generally for overlapping widgets, but not always)
     ImVec2                  ActiveIdClickOffset;                // Clicked offset from upper-left corner, if applicable (currently only set by ButtonBehavior)
     ImGuiWindow*            ActiveIdWindow;
+    ImGuiID                 LastActiveId;                       // Store the last non-zero ActiveID, useful for animation.
+    float                   LastActiveIdTimer;
     ImGuiWindow*            MovingWindow;                       // Track the child window we clicked on to move a window.
     ImGuiID                 MovingWindowMoveId;                 // == MovingWindow->MoveId
     ImVector<ImGuiColMod>   ColorModifiers;                     // Stack for PushStyleColor()/PopStyleColor()
@@ -629,6 +631,8 @@ struct ImGuiContext
         ActiveIdAllowOverlap = false;
         ActiveIdClickOffset = ImVec2(-1,-1);
         ActiveIdWindow = NULL;
+        LastActiveId = 0;
+        LastActiveIdTimer = 0.0f;
         MovingWindow = NULL;
         MovingWindowMoveId = 0;